1. Field of the Invention
The invention relates to the production of methane from carbon monoxide. More particularly, it relates to the preparation of a catalyst formulation of enhanced stability for use in such methanation operations.
2. Description of the Prior Art
The production of low-cost methane as a replacement for natural gas has been the subject of considerable interest in light of the energy requirements of industrial societies throughout the world. The COthane process has been developed in response to such interest and concerns. This process, disclosed in detail in U.S. Pat. No. 4,242,103, is a cyclic, essentially two-step process in which a surface layer of active surface carbon is deposited on a catalyst and is then contacted with steam or hydrogen to convert the active surface carbon to methane and carbon dioxide. The process is repeated in cyclic operations without the need for regenerating the catalyst as a necessary additional step of the cyclic operation.
The disproportionation catalyst used for the COthane process is employed essentially in its metal state and is typically combined with a catalyst support additive and with a binder to ensure that the catalyst has a desired combination of activity, capacity and stability. In the absence of such additives and binders, the preferred catalyst, nickel, for example, is relatively unstable and tends to agglomerate and sinter with resultant reduction of its surface area. With the incorporation of additives and binders into the catalyst formulation, on the other hand, agglomeration and sintering of the catalyst is prevented, and the activity and capacity of the catalyst, and its stability in continuous, cyclic operations can be maintained.
Those skilled in the art will appreciate that the long term stability of the catalyst composition employed in the cyclic COthane process will have a significant effect on the overall technical and economic feasibility of the process for the production of low-cost methane from CO-containing waste gas streams. During repeated use in the cyclic process, the disproportionation catalyst tends to become coated with inactive carbon that eventually reduces the efficiency of the catalyst to the point where its regeneration becomes necessary or desirable. By extending the number of cycles of use of the catalyst between regenerations, the cost of the overall operation can be reduced, facilitating the practice of the COthane process in practical, commercial operations. It is highly desirable in the art, therefore, that the long term stability of the catalyst composition be improved so as to enable the catalyst to be employed satisfactorily in the cyclic COthane process over an extended number of cycles before burn off or other removal of the inactive carbon becomes necessary or desirable.
It is the object of the invention, therefore, to provide an improved disproportionation catalyst for use in the COthane process.
It is another object of the invention to provide a process for the production of a disproportionation catalyst having enhanced stability in long term cyclic operations.
It is a further object of the invention to provide a catalyst having enhanced stability for continuous use in the cyclic COthane process.
With these and other objects in mind, the invention is hereinafter described in detail, the novel features thereof being particularly pointed out in the appended claims.